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Electrostatic discharge information
A sudden discharge of static electricity from your finger or other conductor can destroy static-sensitive
devices or microcircuitry. Often the spark is neither felt nor heard, but damage occurs. An electronic device
exposed to electrostatic discharge (ESD) may not appear to be affected at all and can work perfectly
throughout a normal cycle. The device may function normally for a while, but it has been degraded in the
internal layers, reducing its life expectancy.
Networks built into many integrated circuits provide some protection, but in many cases, the discharge
contains enough power to alter device parameters or melt silicon junctions.
IMPORTANT:
observe these precautions:
Keep components in their electrostatic-safe containers until you are ready to install them.
Before touching an electronic component, discharge static electricity by using the guidelines described in this
section.
Avoid touching pins, leads, and circuitry. Handle electronic components as little as possible.
If you remove a component, place it in an electrostatic-safe container.
Generating static electricity
Note the following:
Different activities generate different amounts of static electricity.
●
Static electricity increases as humidity decreases.
●
Table 3-1
Static electricity occurrence based on activity and humidity
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPs from plastic tube
Removing DIPs from vinyl tray
Removing DIPs from Styrofoam
Removing bubble pack from PCB
Packing PCBs in foam-lined box
Electronic components are multi-packaged inside plastic tubes, trays, or Styrofoam.
NOTE:
As little as 700 volts can degrade a product.
Preventing electrostatic damage to equipment
Many electronic components are sensitive to ESD. Circuitry design and structure determine the degree of
sensitivity. The following packaging and grounding precautions are necessary to prevent static electricity
damage to electronic components.
To prevent damage to the device when you are removing or installing internal components,
Relative humidity
55%
40%
7,500 V
15,000 V
3,000 V
5,000 V
400 V
800 V
400 V
700 V
2,000 V
4,000 V
3,500 V
5,000 V
7,000 V
20,000 V
5,000 V
11,000 V
Electrostatic discharge information
10%
35,000 V
12,000 V
6,000 V
2,000 V
11,500 V
14,500 V
26,500 V
21,000 V
15
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